Information recording medium, apparatus and method for recording or reproducing data thereof

ABSTRACT

An information recording medium stores information transmitted as a transport stream as objects. The management information written to the information recording medium includes object information for managing the recorded objects. The object information includes an access map. The access map manages the MPEG transport stream in block units, each block containing an integer multiple number of ECC blocks. In addition to the specific information for accessing the blocks, the access map also includes an I-picture Included Flag indicating whether each block includes I-picture data. It is therefore possible to randomly access the transport stream, which otherwise lacks random accessibility to the middle of the stream.

The present application is a divisional application of application Ser.No. 09/836,292, filed Apr. 18, 2001, which is a continuation in partapplication of application Ser. No. 09/443,498 by Okada et al., filed onNov. 19, 1999 in the United States, the content of which is incorporatedherein by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates generally to a readable/writableinformation recording medium. More specifically, the invention relatesto an information recording medium for recording multimedia datacontaining information in different kinds of formats, including movingpicture data, still picture data, and audio data; and to an apparatusand method for recording data to and replaying data from the informationrecording medium.

2. Description of Related Art

While the maximum storage capacity of rewritable optical disc media wasrecently 650 MB, phase-change type DVD-RAM media that are now availablecan store several gigabytes. DVD-RAM media are already used in thecomputer industry, and commercialization of the MPEG and MPEG-2 digitalAV data coding standards are expected to bring new uses for DVD-RAMmedia in the audio-video industry.

A major area of interest is how to best use such large capacity opticaldiscs to record image data and other AV data in ways that achievesignificantly greater performance than conventional AV equipment andalso offer new functionality. Furthermore, because AV equipment is not apersonal computer, there are significant limitations in terms of howmuch memory can be provided. It is also necessary to provide aninterface that is easy to use for users who are not computer literate,and that makes it possible to provide functions that are easy tounderstand and manipulate.

Current DVD recorders record MPEG content using a program stream format.Digital broadcasting, however, uses a transport stream format, and it istherefore preferable to directly record content using the same transportstream format. The transport stream is intended for broadcasting andcommunications applications, and thus does not provide for randomlyaccessing the transport stream. In addition, transport stream data isalready digital, and can therefore be recorded without an encodingprocess through the DVD recorder, as is needed to record a programstream. A problem with storing a transport stream of this type to anoptical disc or other medium is that random access, one of the greatestfeatures of disc media, cannot be sufficiently achieved.

Moreover, data input using a transport stream may include dataconforming to different standards and even non-standard data types. Insuch cases, the DVD recorder may not be able to determine the locationof an intra-coded picture, or the identified address may have beenrecorded containing errors. A problem in this case is that when suchdata is replayed, data at the location of the intra-coded picture maycontain errors, and normal playback may not be possible.

SUMMARY OF THE INVENTION

The present invention is directed to solving the aforementioned problemsand an object of this invention is to provide an information recordingmedium for recording an MPEG transport stream which is lacking in theability to access the stream at a random point, in conjunction withother AV streams so as to improve random accessibility. A further objectof this invention is to provide an apparatus and method for recordinginformation to and replaying or reproducing information from theinformation recording medium of the invention.

In a first aspect of the invention, an information recording medium isprovided which stores at least one object containing multiplexed encodedvideo data and encoded audio data, and management information formanaging the one or more objects. The image data includes intra-codedpicture data and inter-coded picture data. The management informationincludes map information for the at least one object, the mapinformation managing the objects in blocks of a fixed length andcorrelating the presentation time of the video data multiplexed to theobjects to the blocks, and the map information indicating which of theblocks constituting the object includes the leading data of theintra-coded picture data.

In a second aspect of the invention, an information recording medium isprovided which stores at least two objects containing multiplexedencoded video data and encoded audio data, and management informationfor managing the at least two objects. The video data includesintra-coded picture data and inter-coded picture data. The at least twoobjects include at least a first object and a second object. The firstobject is an object for which the location of intra-coded picture datain the object is managed by the management information. The secondobject is an object for which the location of intra-coded picture datain the object is not managed by the management information. Themanagement information is information for separately managing the firstobject and the second object, and includes map information for eachfirst object, and the map information correlates a playback time of thecorresponding first object with the location of intra-coded picture dataincluded in the object.

In a third aspect of this invention, a recording apparatus is providedfor recording information to the information recording medium describedabove. The information recording apparatus comprises an interface forinputting the object from an external part, a generating section forgenerating management information corresponding to the input object, anda recording section for recording the object and the managementinformation to the information recording medium. The generating sectionincludes a detection section for determining if a block contained in theinput object includes intra-coded picture data, and a producing sectionfor producing the management information containing map informationbased on the result from the detection section.

In a fourth aspect of this invention, a reproducing apparatus isprovided for reproducing data from the information recording mediumdescribed above. The apparatus comprises a playback section for readingand reproducing the object and management information from theinformation recording medium, a user interface for receiving aninstruction specifying the object to play back, and an instructionspecifying a playback time for starting playback of the object, and acontroller for controlling the playback section. When the specifiedobject is a first object, the controller controls the playback sectionso as to identify picture data which is included in the specified objectand corresponds to the specified playback time based on the mapinformation of the management information, and begin the playback fromthe identified picture data.

ADVANTAGES OF THE INVENTION

The information recording medium of the invention enables the transportstream received from digital broadcast media to be recorded with otherAV streams while also enabling the recorded digital broadcast object tobe reproduced with random access to object content. Information foridentifying the validity of the flag indicating the inclusion ofintra-coded pictures (I-pictures) is also provided in the managementinformation used to manage the stream. This enables even recorders thatare unable to analyze the stream but can record the transport stream torecord the transport stream in a way that enables the recordedinformation to be played back with no problems.

The recording apparatus and method of this invention can thus record atransport stream received via digital broadcast to an informationrecording medium in a manner enabling the recorded transport stream tobe randomly accessed during playback.

The reproducing apparatus and method of this invention can also randomlyaccess a transport stream received via digital broadcast media andrecorded to the information recording medium with other AV streams.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows the relationship between media and AV devices which aretargeted by a DVD recorder according to the present invention;

FIG. 2 is a block diagram of the drive device in the DVD recorder shownin FIG. 1;

FIG. 3A shows the address space on a disc, and

FIG. 3B shows the accumulation of data in the track buffer;

FIG. 4A and FIG. 4B describe the lead-in area, data area, and lead-outarea of the disc;

FIG. 5A and FIG. 5B describe the volume space on the disc;

FIG. 6 show the file system and file structure;

FIG. 7 shows the data structure of MPEG data content recorded to thedisc;

FIG. 8 shows the data structure of a program stream and a transportstream;

FIG. 9 shows the data structure of an MPEG transport stream;

FIG. 10 shows the data structure of an MPEG program stream;

FIG. 11 shows in detail the structure of an MPEG transport streampacket;

FIG. 12A to FIG. 12C 2 shows a PAT table and PMAP table used fortransmitting the structure data of the audio stream and video streamcomposing a program;

FIG. 13 describes the video object structures in a program stream formatand in a transport stream format included in an ECC block;

FIG. 14A describes the data structure of the video managementinformation (video manager), focusing on the VOB table;

FIG. 14B shows the data structure of the map information;

FIG. 15A describes the data structure of the video managementinformation (video manager), focusing on the program chain information(PGC);

FIG. 15B shows the data structure of the program chain information;

FIG. 16 shows the specific relationship among objects, cells, programchain, and access map;

FIG. 17 is a table showing the classification of the access map fordifferent input stream cases;

FIG. 18 is a table showing access map types;

FIG. 19 is a block diagram of a model player according to the presentinvention;

FIG. 20 is a block diagram of a DVD recorder;

FIG. 21 is a block diagram of a DVD player according to the presentinvention;

FIG. 22A shows the basic configuration of an access map for a digitalbroadcast object (D_VOB);

FIG. 22B shows another configuration of an access map for a digitalbroadcast object (D_VOB);

FIG. 23 shows the relationship between the access map and cells whenreplaying a digital broadcast object;

FIG. 24 describes a method of using the access map during specialplayback of a digital broadcast object;

FIG. 25 shows the relationship between the access map and stream whendeleting a digital broadcast object;

FIG. 26 shows a multi-stream compatible access map;

FIG. 27 is a flow chart showing an access map generating process;

FIG. 28 is a flow chart showing a process for adding an entry to eachmap of the access map;

FIG. 29 is a flow chart showing a data playback process referring to theaccess map; and

FIG. 30 is a flow chart showing a specific data playback process.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

The preferred embodiments of the present invention are described belowwith reference to the accompanying drawings.

First Embodiment

(1. DVD Recorder System Concept)

FIG. 1 shows an exemplary interface between a DVD recorder andperipheral equipment used with the DVD recorder.

As shown in FIG. 1, a DVD disc which is just one type of optical disc isloaded into the DVD recorder for recording/reproducing video datato/from the disc. The operation of the DVD recorder is generally doneusing a remote control unit.

Video data can be input to a DVD recorder as an analog or digitalsignal. Analog broadcasts use analog signals, and digital broadcasts usedigital signals. Analog broadcasts are generally received anddemodulated by a receiver, such as one built in to a television, andthen input to the DVD recorder as an analog video signal in the NTSCformat, for example. Digital broadcasts are demodulated into a digitalsignal by a STB (Set Top Box) which serves as a receiver, and then inputto the DVD recorder for recording.

On the other hand, video data recorded to a DVD disc is played back bythe DVD recorder and then output to an external device. DVD recorderoutput can also be an analog signal or digital signal. If the DVDrecorder outputs an analog signal, the signal can be input directly to atelevision. If the output is a digital signal, the signal first passesthrough the STB for conversion to an analog signal, and is then outputto the television for display.

Video can also be recorded to and replayed from DVD discs by devicesother than DVD recorders, including DVD camcorders and personalcomputers. Even when a DVD disc containing video data recorded by adevice other than a DVD recorder is loaded into a DVD recorder, the DVDrecorder can also play back the DVD disc.

Audio information typically accompanies the video information containedin analog and digital broadcasts, in which case the audio information isalso recorded and replayed by the DVD recorder. The video information isgenerally moving picture images (such as a movie), but may also includestill pictures. Still images can be recorded using the snapshot functionof a DVD camcorder, for example.

Digital interfaces between the STB and DVD recorder include IEEE 1394,ATAPI, and SCSI interfaces.

It will also be noted that an NTSC composite video signal is referred toabove by way of example as the signal passed from the DVD recorder tothe television, but a component signal carrying separate luminance andcolor difference signals can be used.

It should also be noted that while an analog interface is commonly usedfor video transmission between the AV device and television, replacingthis analog interface with a digital interface such as DVI is also beingresearched. Connecting the DVD recorder and television by way of adigital interface is naturally expected to follow.

(2. DVD Recorder Functions)

FIG. 2 is a block diagram showing the functions of a DVD recorder. TheDVD recorder has an optical pickup 101 for reading data from DVD-RAMdisc 100, an error correcting code (ECC) processor 102, a track buffer103, a selector switch 104 for changing input to and output from thetrack buffer 103, an encoder 105, and a decoder 106.

As shown in FIG. 2, the smallest unit for recording information toDVD-RAM disc 100 is 2 KB per sector. The ECC processor 102 applies errorcorrection processing in ECC blocks each containing 64 sectors.

It will also be obvious that one sector could be defined as 512 bytes or8 KB. Each ECC block could contain 1 sector, 16 sectors, or 32 sectors.The sector size and number of sectors per ECC block typically increasein conjunction with the increase in the amount of information that canbe recorded.

The track buffer 103 is used for variable bit rate (VBR) recording ofthe AV data as a means of more efficiently recording AV data to theDVD-RAM disc 100. More specifically, since the DVD-RAM disc 100read/write rate (Va) is fixed and the bit rate (Vb) of the AV datacontent (images, in the case of video) changes according to thecomplexity of the AV data, track buffer 103 is used to absorb thesedifferences in the bit rate.

The track buffer 103 can also be used even more effectively so that AVdata can be recorded noncontiguously to the DVD-RAM disc 100. This isfurther described below with reference to FIG. 3A and FIG. 3B.

FIG. 3A shows the address space on the disc. Let us assume that AV datais recorded to continuous area [a1, a2] and to continuous area [a3, a4]as shown in FIG. 3A. Continuous playback of the AV data can bemaintained in such cases by supplying data stored in the track buffer tothe decoder 106 while seeking from a2 to a3. This is illustrated in FIG.3B.

When reading the AV data starts from address a1, the data is input totrack buffer 103 from time t1, and data output from track buffer 103also starts. This means that data accumulates in the track buffer atrate difference (Va−Vb), which is the difference between the trackbuffer input rate (Va) and the track buffer output rate (Vb). Thiscontinues until the data is read to address a2, that is, time t2. Whenthe amount of data accumulated in the track buffer 103 during this timeis taken as B(t2), continuous playback can be sustained by supplyingdata B(t2) accumulated in the track buffer 103 to decoder 106 betweentime t2 and time t3 at which reading data starts from address a3.

In other words, even when a seek occurs, continuous AV data playback ispossible if the amount of data ([a1, a2]) read before the seek starts ismore than or equal to a specified amount.

The size of the continuous area enabling continuous AV data output canbe determined from the following equation by converting to the ECC blockcount (N_ecc).N _(—) ecc=Vb*Tj/((N _(—) sec*8*S_size)*(1−Vb/Va))where N_sec is the number of sectors per ECC block, S_size is the sectorsize, and Tj is the seek performance (maximum seek time).

There are also cases in which there is a defective sector in thecontinuous area. In such cases the continuous area size can be obtainedfrom the following equation obtaining the ECC block count as above.N _(—) ecc=dN _(—) ecc+Vb*Tj/((N _(—) sec*8*S_size)*(1−Vb/Va))where dN_ecc is the allowed defective sector size.

It should be noted that reading, that is, replaying or reproducing datafrom a DVD-RAM disc is considered in the above example, writing, thatis, recording data to DVD-RAM can be handled in the same way.

As described above, it is therefore possible to sustain the continuousplayback and recording with a DVD-RAM disc even when the AV data isnoncontiguously recorded to the disc insofar as the AV data is recordedin continuous blocks of a specific minimum size. This continuous area iscalled CDA in DVD terminology.

(3. DVD Discs)

A DVD-RAM disc, a type of recordable optical disc, is used by way ofexample as the readable/writable information recording medium accordingto this preferred embodiment of the invention.

FIG. 4A and FIG. 4B show the appearance and physical structure of aDVD-RAM disc 100, a type of recordable optical disc, used as thereadable/writable information recording medium in this preferredembodiment of the invention. It should be noted that a DVD-RAM disc istypically housed in a cartridge and then loaded into the DVD recorder.This is to protect the recording surface of the disc. It will also beobvious that if the recording surface is protected by some other means,or if it is acceptable to not use the disc in a cartridge, the disc canbe loaded directed into the DVD recorder.

Data is recorded to a DVD-RAM disc using a phase change method. Datarecorded to the disc is managed in sector units, and is recorded withaddress information enabling data access. A unit of 64 sectors is usedas a unit for error correction, has an error correction code addedthereto, and is referred to as an ECC block.

FIG. 4A shows the recording area of this recordable DVD-RAM disc 100.DVD-RAM disc 100 has a lead-in area at the inside circumference area, alead-out area at the outside circumference, and a data area between thelead-in area and lead-out area. A reference signal, needed to stabilizethe servo for access by the optical pick-up, and an identificationsignal for distinguishing a DVD-RAM disc from other types of opticalmedia, are recorded in the lead-in area. The same reference signal isalso recorded to the lead-out area. The data area is divided intosectors, which is the smallest access unit; each sector stores 2K ofdata in this embodiment. DVD-RAM disc 100 is further divided into pluralzones to enable Z-CLV (Zone Constant Linear Velocity) control of discrotation during recording and playback.

FIG. 4A also shows several of these concentric zones on DVD-RAM disc100. DVD-RAM disc 100 in this examples has twenty four-zones numberedzone 0 to zone 23. The angular velocity of the DVD-RAM disc iscontrolled in each zone such that it increases the closer the zone is tothe inside circumference, and remains constant while the optical pick-upis accessing any same zone. This technique increases the recordingdensity of the DVD-RAM disc, and makes rotational control duringrecording and playback easier.

FIG. 4B shows the lead-in area, lead-out area, and data area zones 0 to23 shown concentrically in FIG. 4A in section view.

Each of the lead-in area and lead-out area has a defect management area(DMA). The defect management area is an area for recording addressinformation for defective sectors, and substitution address informationindicating where the sector substituted for the defective sector islocated in the substitution area.

Each zone area contains a user area, and a substitution area and unusedarea in the zone boundary. The user area is an area used by the filesystem for recording information. The substitution area is an area thatis substituted for a defective sector when a defective sector is found.The unused area is an area that is not used for recording information,and is provided for about two tracks. The reason why the unused area isprovided is as follows. The sector address is recorded to the samelocation in adjacent tracks in a particular zone, but in the Z-CLVcontrol method, the sector address recording position is different inadjacent tracks at the zone boundary, and this may result inmisinterpretation of the sector address. The unused area is provided toprevent this.

As described above, there are sectors at the zone boundaries that arenot used for recording information. So that only those sectors that areused for recording information are shown consecutively, DVD-RAM discsassign a logical sector number (LSN) sequentially from the insidecircumference to each physical sector in the user area.

FIG. 5A and FIG. 5B show the logical data space of a DVD-RAM disc thuscomprising logical sectors. The logical data space is called the volumespace, and is used for recording user data.

Data recorded in the volume space is managed by the file system. Morespecifically, volume structure information for managing one group ofsectors storing data as a file, and one group of files as a directory,is recorded at the beginning and at the end of the volume space. A UDF(Universal Disc Format) file system conforming to ISO 13346 is used asthe file system in this preferred embodiment of the invention.

It will be noted that the group of sectors is not necessarilycontiguously located on the disc, and can be distributed to differentparts of the disc. The file system therefore manages as an extent agroup of sectors that are contiguous in the volume space in the sectorgroup constituting a file, and manages the file as a group of relatedextents.

FIG. 6 shows the structure of a directory and file recorded to a DVD-RAMdisc. The VIDEO_RT directory is located at the root level. Variousobject files, that is, the data objects to be reproduced, and a VideoManager file which is a management information indicating the sequencein which the object files are played back and various attributes, arerecorded under the VIDEO_RT directory.

The objects are data conforming to MPEG-standard, and include PS_VOB,TS1_VOB, TS2_VOB, AOB, and POB. PS_VOB, AOB and POB are the MPEG programstream (PS), while TS1_VOB and TS2_VOB are the transport stream (TS).The program stream has a data structure which is designed for storingthe AV data to a package medium. The transport stream has the datastructure which is designed for communications media.

Each of PS_VOB, TS1_VOB and TS2_VOB contains both video and audio data,and the video data are primary. TS1-VOB object is an object which is inprinciple encoded by the DVD recorder, and of which internal picturestructure can be managed clearly. TS2-VOB object is an object encoded bya device other than the DVD recorder, and a part of internal picturestructure of TS2-VOB object may be unclear.

Typically, TS1-VOB object is an object obtained by encoding the analogvideo signal input from an external source to the transport stream bythe DVD recorder. TS2-VOB object is an object obtained by recordingdirectly the digital video signal input from an external source to thedisc without encoding by the DVD recorder.

AOB and POB objects are part of the MPEG program stream. AOB object isan object comprising primarily audio data, and POB object is an objectcomprising primarily still picture data.

It is noted that “primarily video data” and “primarily audio data”objects as used above means that the bit rate allocation for video andaudio data is great respectively. VOB objects are used for applicationssuch as movies, and AOB objects are used for audio (music) applications.

(4. Outline of Replayed AV Data)

FIG. 7 shows the structure of MPEG data recorded to a DVD disc asvarious types of AV objects.

As shown in FIG. 7 video and audio streams are divided and multiplexed.The multiplexed stream is referred to in the MPEG standard as the“system stream.” In the case of a DVD disc, the system stream havingDVD-specific data is called VOB (Video Object). Unit of division iscalled “pack packet” and has a capacity of approximately 2 Kbytes.

The video stream is encoded according to the MPEG standard andcompressed at a variable bit rate such that the bit rate is increased incomplex images containing, for example, much movement. Under the MPEGstandard video pictures are encoded as an I-picture, P-picture, orB-picture. I-picture is spatially compressed and independently codedwithin a single frame without reference to any other pictures. P-pictureand B-picture are temporally compressed with reference to correlationbetween frames. A block of pictures containing at least one I-picture ismanaged as a “group of pictures” (GOP) under the MPEG system. A GOP isused as an access point for special playback operations such as fastplay because the GOP contains I-picture which is compressed within aframe.

Audio stream encoding for recording to DVD can be accomplished using theMPEG audio standards AAC and MP3, or using AC3 or LPCM encoding methods.

As shown in FIG. 7, the multiplexed data units containing the video datacomposing a GOP and the associated audio data are called VOBUs (VideoObject Units). VOBU may contain data for managing the block of movingimages as header data.

The system stream described in FIG. 7 includes a program stream (PS) anda transport stream (TS). The program stream has a data structureintended for recording to packaged media, while the transport streamdata structure is intended for communications media.

FIG. 8 shows the data structure of the program stream and transportstream.

The program stream comprises a number of fixed-length packs each ofwhich is the smallest unit for transmission and multiplexing. Each packcontains one or more packets. Both of pack and packet have a header partand a data part. The data part is known in MPEG as the payload. Thefixed length of the pack is 2 KB in DVD media to match the sector size.A pack can contain plural packets, but except for special circumstancesone pack contains one packet because a pack storing DVD video or audiodata has only one packet.

The unit for transport stream transmission and multiplexing comprisesthe fixed-length TS packets. TS packet size is 188 bytes forcompatibility with the asynchronous transport mode (ATM) communicationstandard. One or more TS packets compose a PES packet.

The PES packet is a common concept between the program stream and thetransport stream, and the data structure of the PES packet is also thesame between the both streams. A packet stored in a program stream packdirectly compose a PES packet, while one or more TS packets of thetransport stream compose a PES packet.

The PES packet is the smallest encoding unit, and stores video data andaudio data encoded using the same encoding method. That is, video dataand audio data encoded with different coding methods are not containedin a same PES packet. It should be noted that if the same coding methodis used, the picture boundary and audio frame boundary do not have to beassured. As shown in FIG. 8, a combination of plural PES packets maystore a single I-picture, or a single PES packet may contain pluralpictures.

FIG. 9 and FIG. 10 show the individual data structures of the transportstream and program stream, respectively.

As shown in FIG. 9, a TS packet comprises a TS packet header, anapplication field, and payload. The TS packet header contains PID(Program ID) which identify several streams such as the video stream oraudio stream to which the TS packet belongs.

The application field contains the program clock reference (PCR). ThePCR is a value for a reference clock (STC) of a device which decodes thestream. The decoding device typically demultiplexes the system stream atthe timing controlled by the PCR, and then reassembles to the severalstreams such as the video stream.

The PES header contains a decoding time stamp (DTS) and a presentationtime stamp (PTS). The DTS indicates the decode timing for the picture oraudio frames stored in the PES packet, and the PTS indicates thepresentation timing for video and audio output.

It should be noted that the PTS and DTS are not necessarily written toall PES packet headers. Decoding and output can be accomplished insofaras the PTS and DTS are written to the header of the PES packet where thehead data of the I-picture data is stored.

The structure of the TS packet is shown in detail in FIG. 11.

As shown in FIG. 11, a random access presentation flag is stored to theapplication field in addition to the PCR. This flag indicates whether ornot data which is the head of the video/audio frame and can be used asan access point is stored to the corresponding payload. Furthermore, theTS packet header stores, in addition to the above-described PID, a unitstart presentation flag indicating the start of a PES packet, andapplication field control data indicating whether an application fieldfollows.

FIG. 10 shows the structure of the packs composing the program stream.The pack header of each pack contains an SCR and Stream ID. The SCR issubstantially the same as PCR of the transport stream, and the Stream IDis substantially the same as the PID. Because the PES packet datastructure is the same as in the transport stream, the PTS and DTS arealso stored in the PES packet header.

A major difference between the program stream and transport stream isthat the transport stream allows multiple programs. In other words,while the program stream can carry only one program, the transportstream is designed to carry plural programs at the same time. It istherefore necessary for a reproducing apparatus to be able to identifyeither the video stream or audio stream composing a program for eachprogram in the transport stream.

FIGS. 12A to 12C show the PAT table and PMAP table containing the audiostream and video stream structure of each program. As shown in thesefigures, the PMAP table stores information relating to a combination ofvideo stream and audio stream which are used for each program, and thePAT table stores information relating to a combination between programsand PMAP tables. The reproducing apparatus can detect the video streamand the audio stream which are composing a program that is requested tooutput using the PAT table and PMAP table.

Arrangement of packs of the program stream and TS packets of thetransport stream on the disc is described next with reference to FIGS.13A and 13B.

As shown in FIG. 13A, an ECC block comprises 64 sectors. As shown inFIG. 13B, the PS packs composing the video object (PS_VOB) in theprogram stream format are placed at the sector boundary. This is becauseboth the pack size and sector size is 2 KB.

Video object (TS1_VOB, TS2_VOB) in the transport stream format isarranged in ECC block in a unit of 8 KB which is called capsule. Eachcapsule has an header area of 18 byte and a data area. The data areacontains forty three TS packets each containing an additional 6 byteblock of ATS (Arrival Time Stamp) information. The ATS information isinformation generated and added by the DVD recorder, and indicates thetiming at which the packet was sent to the DVD recorder from an externalsource.

(5. AV Data Management Information and Playback Control)

FIGS. 14A and 14B and FIGS. 15A and 15B show the data structure of thefile referred to as a video management information (Video Manager file)shown in FIG. 6.

The Video Manager file contains object information which is managementinformation including locations on the disc where the objects arerecorded, and playback control information indicating the playbacksequence of the plural objects.

In the example shown in FIG. 14A, the objects recorded to disc includePS_VOB#L to PS_VOB#n, TS1_VOB#1 to TSlVOB#n, and TS2_VOB#1 to TS2_VOB#n.

As shown in FIG. 14A, as the object information, there are a PS_VOBinformation table, TS1_VOB information table, and TS2_VOB informationtable, respectively, depending upon the object type. Each table containsVOB information for each object.

The respective VOB information includes general information about thecorresponding object, attributes information of the object, an accessmap for converting playback time of the object to a disc address, andaccess map management information. The general information includesidentification data for the corresponding object, object recording timeand so on. The attribute information include video stream information(V_ATR) containing coding mode of the video stream, the number of audiostreams (AST_Ns), and audio stream information (A_ATR) including codingmode of the audio stream.

There are two reasons why the access map is required. First is to enablethe playback path information to determine where an object is recordedon the disc indirectly based on the object playback time, and thus avoiddirectly accessing objects using, for example, a sector address. In RAMmedium, editing may change the location of objects recorded to RAM. Inthe case that the program chain information references the objectlocation directly by means of the sector address and so on, the amountof playback path information to be updated upon the editing increases.However, if object locations are referenced indirectly based on theplayback time, it is not necessary to update the playback path chaininformation when objects move, and it is only necessary to update theaccess map.

The second reason is that the AV stream generally has two referencesincluding a time-base axis and data (bit sequence) axis, and thecorrelation therebetween is not perfect. In the case of MPEG-2 video, aninternational standard for video stream coding, for example, a variablebit rate (enabling the bit rate to be adjusted according to imagequality and complexity) is being most commonly used. In this case, thereis no directly proportional relationship between the amount of datameasured from the beginning of the stream and the playback time, andthus random access referenced to the time base is not possible. To solvethis problem, the access map is used to convert between the time baseand data (bit sequence) axis.

As shown in FIG. 14A, the playback control information includes auser-defined playback path information table, original playback pathinformation table, and title search pointer.

As shown in FIG. 15A, there are two playback paths including playbackpath information which is originally defined and playback pathinformation freely defined by the user. The originally defined playbackpath information is generated automatically by the DVD recorder uponrecording each object so as to specify all the recorded objects. Theuser-defined playback path information can be defined by the user tospecify a desired playback sequence. This playback path information isuniformly referred to as program chain information (PGC information) inDVD media field, the user-defined program chain information is referredto as U_PGC information, and the original program chain information asO_PGC information. The O_PGC information and U_PGC information bothcompile a sequence of cell information in table form. The cellinformation is information indicative of a cell designating a playbacksection of a particular object, in table form. The playback section ofthe object indicated by the O_PGC information is referred to as aoriginal cell (O_CELL), and the playback section of the object indicatedby the U_PGC information is referred to as a user cell (U_CELL).

The cell indicates the playback section of the object using playbackstart time and playback end time of the object. The start time and endtime are converted by the above-noted access map to the actual recordinglocation of the object on the disc.

As shown in FIG. 15B, the cells defined by the PGC information provide aplayback sequence in which each object designated by the correspondingcell is reproduced in sequential order according to the entry order inthe PGC information table.

FIG. 16 shows the concrete relationship between objects, cells, PGC, andaccess map.

As shown in FIG. 16, PGC information 50 includes at least one of cellinformation 60, 61, 62, 63. Cell information 60, specifies the object tobe played back (reproduced), and further specifies the object type andplayback section of the object. The sequence in which the cellinformation is recorded in the PGC information 50 determines theplayback order of the cells designated by the corresponding cells.

The cell information 60 contains type information (Type) 60 a indicatingthe object type, Object ID 60 b identifying the object, start timeinformation (Start_PTM) 60 c indicating the start time of the cell inthe object on the time base, and end time information (End_PTM) 60 dindicating the end time of the cell in the object on the time base.

When the data is played back, cell information 60, 61, in the PGCinformation 50 is read in sequence, and the object specified by eachcell is reproduced for the playback section specified by the cell.

The access map 80 c converts the object start and end times stored inthe cell information 60, 61, to location information on the disc.

The map information is generated and recorded at the same time as theobjects are recorded. The structure of the pictures in the object datamust be analyzed in order to generate the map. More specifically, it isnecessary to detect the location of the I-pictures (as shown in FIG. 8),and to detect the time stamp information such as PTS which is theplayback time of the corresponding I-picture as shown in FIG. 9 and FIG.10.

Problems that occur when generating the PS_VOB, TS1_VOB, and TS2_VOB mapinformation are described next.

As described with reference to FIG. 1, PS_VOB and TS1_VOB are primarilygenerated when the DVD recorder encodes a received analog broadcastsignal to an MPEG stream. The I-pictures and time stamp data are thusgenerated by the DVD recorder during the encoding process, the internaldata structure of the stream being clearly defined and known to the DVDrecorder. Therefore, there are no problems generating the mapinformation by the DVD recorder.

TS2_VOB, however, is obtained when a received digital broadcast isrecorded directly to the disc without further encoding by the DVDrecorder. The DVD recorder thus does not generate the I-picture locationand time stamp data as it does when recording PS_VOB. As a result, theinternal data structure of the stream is not obvious to the DVDrecorder, and this information must be detected from the recordeddigital stream.

Therefore, for the map information of the TS2_VOB, the DVD recorderdetects I-pictures and the time stamp data as follows.

First, I-picture is detected by detecting random access indicatinginformation (random_access_indicator) in the application field for TSpacket (as shown in FIG. 11). The time stamp is detected by detectingthe PTS of the PES header. For the time stamp, PCR in the applicationfield, or ATS, which is the arrival time of the TS packet to the DVDrecorder, can be used instead of the PTS as the time stamp. In eithercase, the DVD recorder does not analyze the data structure of the videolayer of the MPEG stream, but detects the location of I-pictures usingsystem layer information which is above the video layer. This is becauseanalyzing the video layer to generate the map information imposessignificant overhead on the system.

There are also cases in which system layer detection is not possible. Itis not possible to generate the map information in such cases, and it istherefore necessary to indicate that there is no valid map information.This is indicated by the DVD recorder using the map managementinformation shown in FIG. 14B.

As shown in FIG. 14B, the map management information contains mapvalidity information and a self-encoding flag. The self-encoding flagshows that the object was encoded by the DVD recorder itself, that theinternal picture structure is clear, and that the time stamp informationand I-picture location information in the map information are accurate.The map validity information indicates if there is a valid access mapavailable.

Examples of cases in which the system layer cannot be detected mayinclude when the application field is not provided, or when the originaldigital stream is not an MPEG transport stream. Different digitalbroadcasting system are likely to be adopted in different countries, andtherefore there will likely be cases in which the DVD recorder recordsobjects for which a map cannot be generated. For example, if a DVDrecorder designed for digital broadcasts in Japan is used in the UnitedStates to record a digital broadcast in the United States, there may becases in which objects for which a map cannot be generated will berecorded.

The DVD recorder however will still be able to sequentially reproducefrom the beginning of objects for which map information cannot begenerated. In this case, it is possible to reproduce the video bypassing the recorded digital stream through a digital interface to anSTB operable to process the digital stream.

To summarize, there are four possible cases as shown in FIG. 17depending upon (a) whether the recorded stream is a program stream ortransport stream, (b) whether the stream is self-encoded, and (c)whether I-picture (access unit) detection or address detection ispossible. Note that, an open circle “O” in FIG. 17 indicates thecondition indicated by the column is satisfied, and an “X” indicates thecondition is not satisfied.

Four different access maps as shown in FIG. 18 are thus compiledcorresponding to the four cases shown in FIG. 17. The types of accessmaps are described below. As shown in FIG. 18, the access maps can begrouped into one of four types according to the level of recordingstream analysis.

i) Access Map #1

This access map is compiled and used in case that the recorder analyzesthe internal structure of the recording stream when the access map isgenerated, and access unit location and playback time information cantherefore be obtained. This access map manages the playback time of theaccess unit and disc address of the access units with byte levelprecision.

ii) Access Map #2

This access map is compiled and used in case that the recording streamis a transport stream and is self-encoded, that the location of accessunits is managed in each block of a fixed size of 2 bytes or more, andthat the playback time can be detected. The access map manages theplayback time of the access unit and a block storing the access unit,relating those.

iii) Access Map #3

This access map is compiled and used in the case that the recordingstream is a transport stream and is self-encoded, that the location ofaccess unit is managed in each block of a fixed size of 2 bytes or more,but that the playback time cannot be determined. The access map managesthe arrival time of packets containing the access unit and a blockstoring the access unit, relating those.

iv) Access Map #4

This access map is compiled and used in case that the recording streamis a transport stream and is self-encoded, but that it is unclearwhether the location of access unit is managed in each block of a fixedsize of 2 bytes or more, and that the playback time cannot bedetermined. The access map manages the arrival time of particularpackets. The map validity information flag is set to “invalid” in thiscase.

It is thus possible to generate and select an access map appropriate tothe recording stream based on analysis level of the internal structureof the recording stream. Random access and stable data playback can beachieved when these access maps are used to reproduce an optical disc towhich a transport stream is recorded.

(6. Basic Operation of the Playback Function)

The playback operation of a DVD recorder/player for playing back anoptical disc as described above is described below with reference toFIG. 19.

As shown in FIG. 19 the DVD player has an optical pickup 201 for readingdata from optical disc 100, ECC processor 202 for error correction ofthe read data, track buffer 203 for temporarily storing the read dataafter error correction, PS decoder 205 for reproducing program streams,including video objects (PS_VOB), TS decoder 206 for reproducing thetransport stream of digital broadcast objects (TS1_VOB), audio decoder207 for reproducing audio objects (AOB), still picture decoder 208 fordecoding still picture objects (POB), selector 210 for switching datainput to the decoders 205 to 208, and controller 211 for controlling thevarious components of the player.

The data recorded on the optical disc 100 is read by optical pickup 201,passed through ECC processor 202, and stored to track buffer 203. Thedata stored in the track buffer 203 is then input to one of thedecoders, that is, PS decoder 205, TS decoder 206, audio decoder 207, orstill picture decoder 208 to be decoded and output.

The controller 211 decides what data to be read at this time based onthe playback sequence indicated by the program chain information (PGC)such as shown in FIG. 15. Using the example shown in FIG. 15, thecontroller 211 controls reading so as to first reproduce a partialsection (cell#1) in VOB#1, then reproduce a partial section (cell#2) inVOB#3, and finally reproduce a partial section (cell#3) in VOB #2.

The controller 211 can also obtain the cell types to be reproduced, thecorresponding objects, and the playback start time and end time of eachobject using the cell information of the program chain (PGC) as shown inFIG. 16. The controller 211 uses the cell information to input the datafor the objects identified by the cell information to the appropriatedecoder.

The player according to this preferred embodiment of the invention alsohas a digital interface 204 for supplying the AV stream to an externaldevice. This makes it possible to supply the AV stream to an externaldevice using a communication protocol such as IEEE 1394 or IEC 958. Thisis because the player may not have the decoder needed to decode aTS2_VOB stream that was not encoded by the player, in which case theplayer can directly output the stream via the digital interface 204 toan external STB for reproduction by that STB.

When digital data is output directly to the external device, thecontroller 211 determines whether random access reproduction is possiblebased on the map information such as shown in FIG. 14B. If the accesspoint flag is valid, the access map contains location information of anI-picture. This enables the controller 211 to output to the externaldevice via the digital interface 204 digital data containing anI-picture when there is a request from the external device for fastforward playback or other special playback operation. Time-base accessis also possible if the time access flag is valid. This flag enables thecontroller 211 to output to the external device via the digitalinterface 204 digital data containing the picture data corresponding toa specified playback time when a request is received from the externaldevice to access and play the stream starting at a particular point oftime in the stream.

(7. Basic Operation of the Recording Function)

The configuration and operation of a DVD recorder according to thepresent invention for recording and reproducing an optical disc aredescribed next below with reference to FIG. 20.

As shown in FIG. 20, this DVD recorder has a user interface 211 wherebyinformation is presented to the user and instructions are received fromthe user, a system controller 212 for managing and controlling overalloperation of the DVD recorder, an analog tuner 213 for receiving VHF andUHF signals, an encoder 214 for converting analog signals to digitalsignals to encode into an MPEG program stream, a digital tuner 215 forreceiving digital satellite broadcasts; an analyzer 216 for analyzingthe MPEG transport stream received from a digital broadcast satellite, adisplay unit 217 such as a television and speakers, and a decoder 218for decoding the AV stream. The decoder 218 includes, for example, boththe first and second decoders shown in FIG. 14.

The DVD recorder also has a digital interface 219, track buffer 220 fortemporarily storing the write data, and a drive 221 for writing data toDVD-RAM disc 100. Note that the digital interface 219 is used foroutputting data to an external device according to a communicationprotocol such as IEEE 1394.

With a DVD recorder thus comprised, the user interface 211 firstreceives a request from the user. The user interface 211 then passesthis request to the system controller 212, and the system controller 212then interprets the request and sends requests to appropriate componentsof the DVD recorder.

Let us first consider recording a PS_VOB when a request to record ananalog broadcast is received from the user.

In this case, the system controller 212 instructs the analog tuner 213to receive the broadcast and instructs the encoder 214 to encode thebroadcast signal.

The encoder 214 video-encodes, audio-encodes, and system-encodes the AVdata received from the analog tuner 213, and then passes the encodedoutput to the track buffer 220.

Immediately after encoding starts, encoder 214 sends the playback starttime (PS_VOB_V_S_PTM) of the MPEG program stream being encoded to thesystem controller 212, and then sends the time-base length and size ofthe video object unit (VOBU) to the system controller 212 parallel tothe encoding process in order to generate the T map.

The system controller 212 then outputs a record instruction to the drive221, which in turn reads data from the track buffer 220 and writes toDVD-RAM disc 100. The system controller 212 also gives the drive 221instruction to indicate the location on the disc 100 where the data isrecorded, based on the file system allocation data.

Recording is ended by a stop request from the user. The user inputs astop recording request to the system controller 212 through the userinterface 211, and the system controller 212 then instructs the analogtuner 213 and encoder 214 to stop.

When the stop encoding request from the system controller 212 isreceived, the encoder 214 sends the playback end time (PS_VOB_V_E_PTM)of the MPEG program stream last encoded to the system controller 212.

After the recording process ends, the system controller 212 generatesthe video object information (PS_VOBI) based on the information receivedfrom encoder 214.

Cell information is then generated for this video object information(PS_VOBI), but what is important to note here is that the cell type isset to “PS_VOB”. As described above, data written in the cellinformation is not dependent on the video object (PS_VOB), and all datathat depends on the video object (PS_VOB) is hidden in the video objectinformation (PS_VOBI). Normal playback is therefore not possible if thecell type information is not correctly detected, and in some casesincorrect cell type detection could cause the system to crash.

Finally, the system controller 212 instructs the drive 221 to finishrecording the data in the track buffer 220, and instructs the drive torecord the video object information (PS_VOBI), cell information, andplayback time base information. The drive 221 thus records the remainingdata in the track buffer 220, records video object information (PS_VOBI)and the cell information to DVD-RAM disc 100, and ends the recordingprocess.

It will also be obvious that the analog broadcast can be encoded to aTS1_VOB stream.

Further obviously, encoding is skipped when recording a TS2_VOB streamthat is recorded without encoding.

Analyzer 216 first extracts the start time information (D_VOB_V_S_PTM)from the MPEG transport stream and sends it to the system controller 212in order to generate the digital broadcast object information(TS2_VOBI). The object units (VOBU) in the MPEG transport stream arethen determined, and the time-base length and size of the object unitsneeded for T map generation are sent to the system controller 212. Notethat the object units (VOBU) can be determined by detecting therandom_access_indicator in the adaptation field of the TS packet headeras described above.

The system controller 212 then sends a record instruction to the drive221. The drive 221 then reads data from the track buffer 220 and recordsit to the DVD-RAM disc 100. The system controller 212 also tells thedrive 221 where the data is recorded on the disc 100 based on the filesystem allocation data.

Recording ends when a stop recording request is received from the user.The stop recording request is passed from the digital interface 219 tothe system controller 212, which in turn provides requests for stoppingprocess of the digital tuner 215 and the analyzer 216.

The analyzer 216 stops stream analysis when the stop request is receivedfrom the system controller 212, and sends the final presentation endtime (D_VOB_V_E_PTM) of the video object unit (VOBU) last analyzed inthe MPEG transport stream to the system controller 212.

After receiving a digital broadcast ends, the system controller 212generates the digital broadcast object information (D_VOBI) based onthis information received from the analyzer 216. Cell informationcorresponding to this digital broadcast object information (D_VOBI) isthen generated with the cell attribute field set to “D_VOB”. Playbacktime information is also generated.

Finally, the system controller 212 instructs the drive 221 to finishrecording the data stored to the track buffer 220, and to record thedigital broadcast object information (D_VOBI), cell information, andplayback time information. The drive 221 thus records the remaining datain the track buffer 220, the digital broadcast object information(D_VOBI), cell information, and playback time information to the DVD-RAMdisc 100, and then the recording process ends.

It will be obvious that while the above operation is described based onstart and stop recording requests input by the user, DVD recorderoperation is substantially the same when a timer recording function suchas available on VCR decks is applied to record automatically, in whichcase the start and stop requests are generated automatically by thesystem controller instead of the user.

(Playback by DVD Recorder)

The playback operation of the DVD recorder is described next.

The user interface 211 receives a request from the user. The userinterface 211 passes the request from the user to the system controller212, which then interprets the request to send control commands to theappropriate modules. When the user request is to playback PGC, thesystem controller 212 interprets the PGC information and cellinformation to determine which objects are to be reproduced. Note thatthe following description assumes an original PGC including one videoobject (M_VOB) and one cell information.

The system controller 212 first analyzes the attribute informationcontained in the cell information of the PGC information. It is knownthat the AV stream to be reproduced is an AV stream recorded as an MPEGprogram stream if the attribute information is set to “M_VOB”.

The system controller 212 then extracts the associated video objectinformation (M_VOBI) from a table (M_AVFIT) based on ID of the cellinformation. Next, the start and end addresses of the AV data to bereproduced are obtained from the start and end addresses of the cellinformation, the video object start time (M_VOB_V_S_PTM) and end time(M_VOB_V_E_PTM), and T map.

The system controller 212 then sends to the drive 221 a request forreading data from the DVD-RAM disc 100 with the address to be read. Thedrive 221 then reads the AV data from the address indicated by thesystem controller 212, and stores the data to the track buffer 220.

The system controller 212 then requests the decoder 218 to decode theMPEG program stream. The decoder 218 reads and decodes the AV data fromthe track buffer 220. The decoded AV data is then output through thedisplay unit 217.

The drive 221 tells the system controller 212 when it has read all dataspecified by the system controller 212. The system controller 212 thensends a stop playback request to the decoder 218. The decoder 218continues reproducing the data until the track buffer 220 is emptied.Once the track buffer 220 is empty and all buffered data has beendecoded and reproduced, the decoder 218 reports to the system controller212 that the reproduction (playback) has finished, and the playbackprocess ends.

The above operation is described using an original PGC consisting of onevideo object (M_VOB) and one cell information. However AV streamplayback can be accomplished using the same process when the originalPGC contains only one digital broadcast object (D_VOB), contains pluralvideo objects, contains plural digital broadcast objects, or contains acombination of video objects and digital broadcast objects.

Audio objects (AOB) and still picture objects (S_VOB) can also bereproduced using the same basic operation and modules, except that theinternal configuration of the decoder 218 will differ somewhat. In thiscase, the decoder 218 comprises PS decoder 205, TS decoder 206, audiodecoder 207, and still picture decoder 208.

A case in which the decoder 218 has no ability to reproduce any AVstreams is described next.

If the decoder 218 does not have the ability to reproduce the MPEGtransport stream, the MPEG transport stream cannot be reproduced by thedecoder 218. In this case, the data is supplied to an external device byway of the digital interface 219 for reproduction by the externaldevice.

When the system controller 212 detects that the cell information in thePGC that the user wants to play is a digital broadcast object (D_VOB)not supported by the system, the system controller 212 sends a dataoutput request to the digital interface 219 instead of sending aplayback request to the decoder 218. The digital interface 219 thenoutputs the AV data stored to the track buffer 220 according to thecommunication protocol of the connected digital interface. Other thanthis, operation is the same as when reproducing a video object (M_VOB).

The system controller 212 can also determine whether the decoder 218 canhandle the AV stream to be reproduced, or the system controller 212 canask the decoder 218 if it can decode the AV stream.

(DVD Player)

The configuration of a DVD player according to the present invention forreproducing an optical disc is described next with reference to FIG. 21.This DVD player is an embodiment of the above described player model.

As shown in FIG. 21, this DVD player has a user interface 2001 wherebyinformation is presented to the user and instructions are received fromthe user, a system controller 2002 for managing and controlling overalloperation of the DVD recorder, a display unit 2003 such as a televisionand speakers, a decoder 2004 for MPEG stream decoding, a digitalinterface 2005 for providing an IEEE 1394 or other connection, a trackbuffer 2006 for temporarily storing data read from DVD-RAM disc 100, anda drive 2007 for reading data from DVD-RAM disc 100. The DVD player thuscomprised performs the same playback operation as the DVD recorderdescribed above.

It will be obvious that while this embodiment is described using DVD-RAMmedia by way of example, the same operations can be applied to othertypes of media, and the present invention shall not be limited toDVD-RAM discs or other types of optical discs.

Furthermore, this embodiment is also described as reproducing an AVstream not supported by the decoder by passing the AV stream through thedigital interface. It will also be obvious that even AV streamssupported by the decoder can be output to an external device through thedigital interface in response to an appropriate user request.

Furthermore, the audio data and still picture data are described asbeing non-MPEG stream data, but the MPEG system stream can also be usedfor audio data and still picture data.

Second Embodiment

The second embodiment of the present invention is described next belowusing exemplarily DVD recorder and DVD-RAM media.

The basic configuration and operation of a DVD recorder and DVD-RAMmedia in this embodiment are the same as described above in the firstembodiment. Further description thereof is thus omitted below. Thefollowing description focuses particularly on the structure of theaccess map for a digital broadcast object (D_VOB) which is of a dataobject type used for digital broadcasts.

(Pcr Map and Pts Map)

An access map in this embodiment of the invention is shown in FIG. 22Aand described below. As shown in FIG. 22A, access map 86 c has two maplayers, PCR map 811 and PTS map 813.

When recording a digital broadcast object (D_VOB) to disc, the stream isrecorded referenced to the ECC block. This means that stream recordingalways starts from the leading sector in the ECC block.

The access map manages objects in block units containing a specificnumber (N) of ECC blocks where N is an integer of 1 or more and is fixedwithin the stream. This unit of N blocks that is used as the managementunit of the access map is referred to below as simply a “block.” Oneblock contains a plurality of transport packets. In the example shown inFIG. 22A, the twentieth block 210, for example, contains pluraltransport packets 210 a, 210 b, 210 c, and so forth.

PCR map 811 is a table in which the entries correspond to the blocks.There are, therefore, as many table entries as blocks. PCR map 811manages a Program Clock Reference (PCR) and I-picture Included Flag foreach entry. The PCR is attached to the transport packet disposed to thebeginning of the block to which the entry refers, and the I-pictureIncluded Flag is associated with the same block.

The PCR indicates the input time of the data to the decoder. TheI-picture Included Flag indicates whether I-picture data of the MPEGvideo data is included in the block. I-picture Included Flag with avalue of “1” means that the block contains an I-picture, in thisexemplary embodiment. The twentieth entry in PCR map 811 shown in FIG.22A, for example, contains the value (“100”) of the PCR attached to thefirst transport packet 210 a in the twentieth block 210, and theI-picture Included Flag (=1) to the twentieth block 210.

PTS map 813 is a table for managing the Presentation Time Stamp (PTS) ofeach I-picture in a digital broadcast object (D_VOB). More specifically,PTS map 813 stores the PTS for each I-picture, and an index value to theblock number of the block in which the I-picture is stored. If theI-picture is stored across plural blocks, the index points to only thenumber of the first block where the I-picture is stored. It is knownfrom PCR map 811 in FIG. 22A that I-pictures are stored from blocks 20to 22. In this case, the fifth entry to PTS map 813 stores, as an index,number (“20”) of the first block in the group of blocks in the PCR mapcontaining I-pictures, and the PTS (“200”) of the same first block.

As shown in FIG. 22A, PCR map 811 has one entry per block, and the orderof the entries in PCR map 811 corresponds to the number of the blockwhich each entry points. Therefore, in the index for PCR map, the blocknumber of the block corresponding to PTS is specified using the sequencenumber of the PCR entry in the PCR map 811.

When the PTS information is available, it is also possible to generateonly the PTS map as shown in FIG. 22B. The PTS map 813 b generated inthis case contains data pairs including the PTS time information (“10”,“200”, and “500” in this example) and the location of the correspondingtransport packets (“1”, “20”, and “45”). This PTS map 813 b can be usedto reproduce and control transport packet for reproduction. This PTS map813 b shows the location of the first or head packet in transportpackets containing an I-picture. Since the access map 86 d contains onlythe PTS map 813 b pointing the first packet locations, using the PTSaccess map 86 d offers the benefit of reducing the amount of managementinformation in comparison with using the access map 86 c shown in FIG.22A.

It will also be apparent that while PCR map 811 is generated so that aflag is set for every block containing an I-picture in the case shown inFIG. 22A, the invention shall not be so limited. It is also possible toset the flag only for the first or last one of blocks containing anI-picture. This also offers the benefit of reducing the amount ofmanagement information.

It is also possible to control transport packet playback moreefficiently and simply by using a table in which flags are set for onlythe first one of blocks containing an I-picture in combination with atable in which flags are set for only the last one of blocks containingan I-picture.

Furthermore, while PTS and PCR information are used as time informationin the tables shown in FIG. 22A and FIG. 22B, it is alternativelypossible to use ATS (Arrival Time Stamp) information indicating thetiming when a packet is sent out from the DVD recorder.

(Playback Using the PCR Map and PTS Map)

A method for reproducing digital broadcast objects (D_VOB) from the PGCinformation using PCR map 811 and PTS map 813 is described next belowwith reference to FIG. 23.

The structure of the digital broadcast object information (D_VOBI) isdescribed first. It should be noted that the structure of the digitalbroadcast object information (D_VOBI) in this embodiment issubstantially identical to that described above in the first embodiment,and the differences therebetween are therefore described below.

As shown in FIG. 23, digital broadcast object general information(D_VOB_GI) 86 a contains an I-picture flag validity flag 821 and blocksize information (block size) 823.

The I-picture flag validity flag 821 indicates the validity of theI-picture Included Flag in each of the above-noted PCR entries. Blocksize information 823 indicates the block size, which consists of N ECCblocks as noted above.

I-picture flag validity flag 821 identifying the validity of theI-picture Included Flag is provided so that the validity of theI-picture Included Flag can be determined so as to prevent erroneousrecognition of the I-picture Included Flag during playback when thetransport stream is recorded without the transport stream being analyzedand I-picture locations identified.

A digital broadcast object playback procedure is described next below.

The structure of the program chain information (PGCI) and cellinformation (CellI) is the same as described in the first embodiment.However, the start and end position information (Start, End) of thedigital broadcast objects stored in the cell information indicate thevalue of the PCR in the transport stream.

When the digital broadcast object is reproduced, the location to startreading the digital broadcast object is determined as follows based onthe start address information stored to the cell information. When thecell information is stored in the user-defined PGC information, thisstart address indicates the desired start time specified by the user,and reading is thus by random access.

First, the time stored to the start address is compared with each PCRvalue stored to PCR map 811 to detect the i-th entry in the PCR mapmeeting the following condition.PCR#i−1≦Start≦PCR#i  (1)where the PCR of the x-th entry is referred to PCR #x. The x-th entry isalso referred to below as entry #x. In addition, the operation ofreferencing the PCR values to obtain the map entry corresponding to thestart address information is referred to as “mapping.”

The I-picture flag validity flag 821 of the digital broadcast objectgeneral information (D_VOB_GI) is then checked to determine if the flag821 is valid. If it is, the I-picture Included Flag for PCR entry #i ischecked. If an I-picture is not contained in the block (the flag valueis “0”), the next PCR entry or PCR entry #i+1 is checked in the sameway. This search continues forward (normal playback direction) until thefirst block in the group of blocks containing an I-picture is found.

If the I-picture Included Flag of the PCR entry #i first checkedindicates that the corresponding block contains an I-picture (the flagvalue is “1”), then the search repeats in the direction of PCR entry#i−1 (that is, in reverse, opposite the normal playback direction) tofind the head PCR entry for the I-picture. The block indicated by thePCR entry thus found is the block at which playback starts.

The time indicated by the end address information (End) in the cellinformation is then compared with each PCR value stored to PCR map 811to detect entry #j in the PCR map satisfying the following condition.Thus, the last block to be reproduced can be identified.PCR#j−1≦End≦PCR#j  (2)

The start playback block and the end playback block identified by theabove procedure are then converted to digital broadcast object (D_VOB)address values using the block size data in the digital broadcast objectgeneral information (D_VOB_GI), and then converted to the address of thefile where the digital broadcast object is stored. The data is then readfrom this file using the obtained address, and the read data is decodedand reproduced.

The entry indicating the start playback block obtained from the PCR map811 is then found in the PTS map 813 by cross-referencing the PCR map811 entry to the PTS map 813 using the index. The decoder can becontrolled so as to not present the input stream until the timeindicated by the PTS by applying the PTS obtained by searching PTS map813 to the decoder as the presentation start time.

It is also possible to determine the location of the playback blocks toreproduce data using an access map having only the PTS map shown in FIG.22B.

It is also possible to determine the location of the playback blocks toreproduce the data by using an access map in which flags are set onlyfor the first one of blocks containing an I-picture or set only for thelast one of blocks containing an I-picture. The location of the block tobe reproduced can be identified even more efficiently and data playbackcontrol can be yet further simplified, by combining a table in whichflags are set only for the first one of the blocks with a table in whichflags are set only for the last one of the blocks.

Random access playback of recorded digital broadcast objects can thus beachieved using an optical disc according to this preferred embodiment ofthe invention.

(Special Playback Operations)

An exemplary special playback operation, specifically fast-forwardplayback, is described next with reference to FIG. 24.

Special playback operations are accomplished by referencing theI-picture Included Flag described above.

The maximum I-picture size is 224 KB, and I-picture is thereforegenerally segmented to and recorded to plural blocks. Special playbackmodes are therefore accomplished by reproducing units of consecutive PCRentries of which the I-picture Included Flags are set to “1”.

Let us assume that in FIG. 24 the I-picture Included Flag is set foreach PCR entry, for example. Playback unit of I-picture comprises PCRentries #n+3 to #n+5 in each of which the I-picture Included Flag is seton. Data corresponding to these entries are read from the storage fileand decoded for reproduction. When reading the blocks corresponding toPCR entries #n+3 to #n+5 is finished, skip is made to PCR entry #n+12where the next I-picture Included Flag is set on in order to reproducethe next I-picture. The above process can be repeated to perform variousspecial playback operations such as fast-forward play as describedabove. It will also be obvious that fast play in reverse can besimilarly accomplished by simply skipping the I-picture playback unitsin reverse.

(Erase Operation)

An erase operation is described next with reference to FIG. 25.

The method for detecting the erase interval is basically the same asduring the playback process. That is, the PCR entries corresponding tothe start and end positions specified by the user are found, and theI-picture Included Flag of the entry at the start of the erase intervalis checked. It is important to note here that the block containing thebeginning of the I-picture is not the block at which erasing starts(start erase block), but rather the block following immediatelythereafter is the start erase block.

This is because the block containing the start of the I-picture alsocontains last data of the previous GOP (Group of Pictures). Therefore,if the block containing the start of the I-picture is erased, normalplayback all the way to the end of the previous GOP will not bepossible.

In the erasing operation, the same operation to the end block at whicherasing ends (end erase block) is performed as that to the start eraseblock. That is, as shown in FIG. 25, if the I-picture Included Flag isset off at the PCR entry #n−1 specified by the user as the erase endlocation, the next entry following entry #n−1 of which the I-pictureIncluded Flag is set on is tried to be found. When the next entry havingthe I-picture Included Flag set on is found, the block indicated by thePCR entry immediately before the found entry is used as the end eraseblock. In the example shown in FIG. 25, the PCR entry which followsentry #n−1 and first has the I-picture Included Flag set on is PCR entry#n+1, and therefore the block indicated by the entry #n immediatelybefore the entry #n+1 is the end erase block. Yet more specifically, theblocks indicated by entries #1 to #n are erased.

On the other hand, if the I-picture Included Flag is set on for entry#n−1 indicated by the user as the end of the erase interval, then thePCR entry having the I-picture Included Flag turned off is searched forin the opposite direction, that is, the reverse direction. When thefirst PCR entry having the I-picture Included Flag turned off is found,the block indicated by that PCR entry is designated as the end eraseblock.

After the start and end erase blocks are identified as described above,the data stored from the start erase block to the end erase block isdeleted, and the PCR entries corresponding to those blocks are deletedfrom the PCR map 811.

As shown in FIG. 25, the PTS entries in PTS map 813 pointing to the PCRentries deleted from the PCR map are also deleted, and the index numbersof the remaining PTS entries are decremented by the number of deletedPTS entries.

When a middle part of a digital broadcast object (D_VOB) is deleted sothat a front portion and a rear portion of the digital broadcast objectremain, entries corresponding to the deleted portion are erased from thePCR map and PTS map for the front portion of the digital broadcastobject. For the rear portion of the digital broadcast object, theentries to the deleted portion are likewise erased from thecorresponding PCR map and PTS map, and the index numbers in the PTS mapare likewise adjusted as described above.

(Multistream)

The application to multistream data is described next with reference toFIG. 26.

Plural video streams can be multiplexed together to an MPEG transportstream. If there are N video streams, then the number of multiplexedvideo streams (Number_of_Streams) 831 is written to the digitalbroadcast object general information (D_VOB_GI) as shown in FIG. 26.

In this case, the I-picture Included Flag field of the PCR entries isexpanded according to the respective N number of streams in the PCR map811. In PTS map 813, the PTS field for the I-pictures in the PTS entriesis likewise expanded according to the N number of streams.

(Recorder)

The structure and basic operation of the recorder are substantiallyidentical to those described in the first embodiment.

What is important to note in the present embodiment is that analyzer1906 generates the above-described PCR map and PTS map. If the recorderdoes not have the ability to generate the PTS map, that is, if it cannotanalyze the MPEG stream to detect the video data, all I-picture IncludedFlags in the PCR entries are cleared to 0, and the I-picture flagvalidity flags in the D_VOB_GI are also turned off (set to “invalid”).

The process whereby analyzer 1906 generates the access map is describedin detail below with reference to the flow charts shown in FIGS. 27 and28.

As shown in FIG. 27, the first step is to set both counter M whichindicates the added entry number to PCR map 811, and counter N whichindicates the added entry number to PTS map 813, to 1 (S11). It isdetermined whether the entry adding process (S13) described below hasbeen completed for the data in all objects specified by the cellinformation in the PGC (S12), and the entry adding process (S13) isapplied to the data for all specified objects.

FIG. 28 is a flow chart of the entry adding process (S13).

When data for one or more blocks is input to the track buffer (S21),data for one block is removed (S22), and Nth entry (entry #N) indicatedby the counter N is added to the PCR map (S23).

The PCR value of the leading transport packet contained in the blockcorresponding to the entry is recorded as the PCR value for PCR entry #N(S24). It is determined whether that block contains an I-picture (S25).If the block contains an I-picture, the I-picture Included Flag of PCRentry #N is set on (“1”) (S26), otherwise, the I-picture Included Flagfor PCR entry #N is set off (“0”) (S34).

Then it is determined whether that block contains a PTS (S27). If not,the process moves to step S33. If the block contains a PTS, it isdetermined whether a specified amount of time has passed since theprevious PTS entry was added (S28). In other words, an entry is notadded to PTS map 813 for every block that contains a PTS, but only sothat there is one entry for a block including PTS per specified timeinterval. This limits the size of the PTS map 813.

If step S28 determines that this specified time since the previous PTSentry was added has not elapsed, control passes to step S33. If thisspecified time has elapsed since the previous PTS entry was added, a newentry is added to the PTS map 813 (S29). More specifically, an M-thentry (entry #M) as indicated by the counter M is added to PTS map 813.The PTS value of the block is stored as the PTS value of PTS entry #M(S30), the value of counter N is stored as the index for PCR map to PTSentry #M (S31), and N is then incremented (S32). Counter M is thenincremented in step S33, and this process ends.

(Player)

The structure and basic operation of the player in this embodiment aresubstantially identical to those described in the first embodiment.

What is important to note is that as described in this embodimentregarding the playback start and end position information in the cellinformation, the start and end playback blocks is obtained byreferencing the PCR map and I-picture Included Flags.

Playback process referencing the access map is described in detail belowusing the flow charts in FIGS. 29 and 30. Note that system controller2002 runs this process.

As shown in FIG. 29, counters M and N are first set to 1 (S51). It isdetermined whether the playback process (S53) described below has beencompleted for the data in all objects specified by the cell informationin the PGC (S52), and the playback process (S53) is performed for allobject data.

FIG. 30 is a flow chart of this playback process (S53). In this playbackprocess, the specified objects are reproduced from the specifiedplayback start time to the specified playback end time.

The start time (Start) and end time (End) specified in the cellinformation are first mapped to entries in the PCR map 811. That is, thePCR map 811 is searched to find the PCR entries #i and #j satisfying thefollowing equations from the specified start and end times (S61).PCR#i≦Start≦PCR#i+1  (3)PCR#j≦End≦PCR#j+1  (4)

The I-picture flag validity flag in the object general information isthen checked to determine whether the I-picture Included Flaginformation is in the PCR map 811 (that is, whether the I-pictureIncluded Flag is valid) (S62). If the I-picture Included Flaginformation is thus determined to not be present in the PCR map 811(that is, the I-picture Included Flag information is invalid) (S63), thecontrol steps to step S67.

If the I-picture Included Flag information is present in the PCR map 811(that is, the I-picture Included Flag information is valid) (S63), it isdetermined whether the I-picture Included Flag for PCR entry #i is on(S64). When the I-picture Included Flag is on for PCR entry #i, PCR map811 is searched back (in the temporally earlier direction) from entry #ito find entry #k containing the leading of the I-picture (S65). That is,this search finds the greatest value of k which provides PCR entry #k inwhich the I-picture Included Flag is off, where k≦i. The value of #i isthen set to i=k+1 (S66), and the control steps to step S67.

If the I-picture Included Flag is not on for PCR entry #i (S64), the PCRmap is searched downstream (the temporally later direction) from entry#i to find entry #k containing the leading of the I-picture (S69). Thissearch finds the smallest value of k which provides the PCR entry #kwhere the I-picture Included Flag is on, where k≧i. The value of i isthen set to i=k (S70), and the control passes to step S67.

Step S67 then calculates the start offset address and end offset addressusing the following equations.start offset address=block size*i  (5)end offset address=block size*j  (6)

The data are then read sequentially from the file based on the startoffset address and the end offset address to pass to the decoder forplayback (S68).

(Variations)

The above embodiments are described using I-pictures in the objects asthe access point data when compiling the access map. It is alternativelypossible, however, to use the “reference picture” in the MPEG-4standard, or other independently presentable picture data.

It will also be noted that streams are recorded in ECC block units inthe present embodiments, but the same effects can be achieved usingother fixed-length block units, and the invention shall not be limitedto operating in ECC block units. Furthermore, the block units aredescribed as fixed in the stream, but the block units can alternativelybe fixed units on the optical disc.

Yet further, while the PCR values of the transport stream are the valuesstored to the PCR map in the above embodiments, the system clockreference (SCR) values of the program stream, or the input time to thesystem decoder, can alternatively be used.

Yet further, while a flag (I-picture Included Flag) is provided in thesepreferred embodiments to identify whether an I-picture is contained in aparticular block, a flag (Reference Picture Included Flag) whichconsists of plural bits and identifies whether the block contains anI-picture or P-picture can alternatively be used.

In data playback or erase operation, PCR entry #i at which the playbackor erasing operation starts is obtained from the start locationinformation in the cell information (CellI) using equation (1), but thevalue of #i can alternatively approximated using the following equation.PCR#i≦Start≦PCR#i+1  (7)

As also described above, in the playback operation, the I-pictureIncluded Flag of the PCR entry is checked in order to detect the startplayback block. If an I-picture is not contained in the block, searchingthe PCR entry continues in the temporally following direction. It isalternatively possible, however, to detect the I-picture Included Flagin temporally preceding PCR entries to return to the first block of thepreceding I-picture.

Furthermore, in the playback operation, it is also described above tocheck I-picture Included Flag to find the start playback block, to checkthe temporally preceding PCR entries when an I-picture is present in theblock, and then to skip back to the beginning of the I-picture. It isalternatively possible, however, to search forward in the temporallyfollowing direction to find the PCR entry for a block containing anI-picture, and then skip forward to the beginning of the next I-picture.

As described above, in the erasing operation, to find the start eraseblock, the I-picture Included Flags are detected, and If an I-picture isnot included then the temporally preceding PCR entry is found to detectthe start erase block. It is alternatively possible, however, to findthe temporally following PCR entry to detect the start erase block.

As also described above, in the erasing operation, to find the starterase block, the I-picture Included Flags are detected, and If anI-picture is included then the temporally following PCR entry is foundto detect the start erase block. It is alternatively possible, however,to find the temporally preceding PCR entry to detect the start eraseblock.

For playback and erasing operations, the block number “j” of the blockwhere playback or erasing ends is obtained from the end locationinformation of the cell information using equation (2) above, but thefollowing equation can alternatively be used to find the end block inthe opposite direction.PCR#j≦End≦PCR#j+1  (8)

Furthermore, during playback operation, when the end playback blockdetermined from the end playback section specified by the user includesan I-picture, the first one of blocks containing the same I-picture canbe searched either forward or backward and identified as the end blockfor playback in the same way as the start block is detected.

It is yet further possible during playback to simply map the start orend block indicated by the user to a PCR entry, and use the location ofthe mapped block as the start or end playback position withoutconsidering the presence of an I-picture (that is, without moving to theblock including the beginning of the I-picture).

As also noted above during the erase operation, the start and end eraseblocks are determined by detecting the beginning of an I-picture. Thisoperation can be omitted and the start and end positions of the group ofblocks to be actually deleted can be determined by simply mapping thestart and end blocks of the segment indicated by the user to therespective adjacent blocks.

The PTS map and PCR map are also described as being expanded the samenumber (N) of fields when there are N multiple streams, but it is alsopossible to prepare in advance the maps to include a fixed number of Mfields (where M≧N), and use only N fields during recording. The value ofN is stored to the Number_of_Streams field of the digital broadcastobject general information (D_VOB_GI) in this case.

Furthermore, an I-picture Included Flag is set in each PCR entry in thepresent invention, but it is alternatively possible to set informationother than the I-picture Included Flag in each PCR entry. Such possiblealternative information include a flag indicating the beginning of anI-picture, a flag indicating the end of an I-picture, or informationindicating the size of the I-picture. These information can also be usedto identify the block from which playback or erasing operations start.

It will also be noted that while the present invention is described withreference to an optical disc, an optical disc recorder, and an opticaldisc player, the invention shall not be so limited. It will be obviousthat the same effects can be achieved whether the MPEG transport streamis recorded to a hard disk or other type of media, and the inventionshall not be limited to physical media.

Although the present invention has been described in connection with thepreferred embodiments thereof with reference to the accompanyingdrawings, it is to be noted that various changes and modifications willbe apparent to those skilled in the art. Such changes and modificationsare to be understood as included within the scope of the presentinvention as defined by the appended claims.

1. An information recording apparatus for recording information to aninformation recording medium for storing at least two objects containingmultiplexed encoded video data and encoded audio data, and managementinformation for managing the at least two objects, the video dataincluding intra-coded picture data and inter-coded picture data, the atleast two objects including at least a first object and a second object,the first object being an object for which a location of the intra-codedpicture data in the object is managed by the management information, thesecond object being an object for which a location of the intra-codedpicture data in the object is not managed by the management information,the first object being of a different type than the second object, themanagement information being information for separately managing thefirst object and the second object, and including map information foreach first object, and the map information correlating a playback timeof the corresponding first object with the location of the intra-codedpicture data included in the corresponding first object, the apparatuscomprising: an interface for inputting an object from an external part;a generating section for generating management information correspondingto the input object; and a recording section for recording the inputobject and the management information to the information recordingmedium, wherein the generating section includes a detection section fordetermining if a block contained in the input object includesintra-coded picture data, and a producing section for producing themanagement information containing map information based on a result fromthe detection section, wherein the management information has, asinformation to identify the first object and second object, a validityflag which indicates whether the map information for each first objectand second object is valid, and wherein the generating section isfurther for determining whether the input object is a first object or asecond object, generating the management information including the mapinformation for the first object, and setting the validity flag in themanagement information to a valid state, when the input object isdetermined to be a first object, and generating the managementinformation for the second object, and setting the validity flag in themanagement information to an invalid state, when the input object isdetermined to be a second object, wherein the management informationincludes path information for indicating a playback sequence of theobject, the path information managing a time domain of the object, andthe map information is a map for converting the time domain of theobject to an address domain of the object.
 2. A method of recordinginformation to an information recording medium for storing at least twoobjects containing multiplexed encoded video data and encoded audiodata, and management information for managing the at least two objects,the video data including intra-coded picture data and inter-codedpicture data, the at least two objects including at least a first objectand a second object, the first object being an object for which alocation of the intra-coded picture data in the object is managed by themanagement information, the second object being an object for which alocation of intra-coded picture data in the object is not managed by themanagement information, the first object being of a different type thanthe second object, the management information being information forseparately managing the first object and the second object, andincluding map information for each first object, and the map informationcorrelating a playback time of the corresponding first object with thelocation of the intra-coded picture data included in the correspondingfirst object, the recording method comprising: inputting the object froman external part; generating management information for the inputobject; and recording the input object and the management information tothe information recording medium, wherein the generating includesdetecting whether the input object is a first object or a second object,and if the input object is a first object, determining if a blockcontained in the input object includes the intra-coded picture data, andproducing the management information containing the map informationbased on a result of the determining, wherein the management informationhas, as information to identify the first object and the second object,a validity flag which indicates whether the map information for eachfirst object and second object is valid, and wherein the generatingfurther includes determining whether the input object is a first objector a second object, when the input object is determined to be a firstobject, generating the management information including the mapinformation for the first object, and setting the validity flag of themanagement information to a valid state, and when the input object isdetermined to be a second object, generating the management informationfor the second object, and setting the validity flag in the managementinformation to an invalid state, wherein the management informationincludes path information for indicating a playback sequence of theobject, the path information managing a time domain of the object, andthe map information is a map for converting the time domain of theobject to an address domain of the object.
 3. An information recordingmedium having stored thereon at least two objects containing multiplexedencoded video data and encoded audio data, and management informationfor managing the at least two objects, the management information beingused to reproduce the audio and video data in a reproduction apparatus,wherein the video data includes intra-coded picture data and inter-codedpicture data, the at least two objects include at least a first objectand a second object, the first object is an object for which a locationof intra-coded picture data in the object is managed by the managementinformation, the second object is an object for which the location ofintra-coded picture data in the object is not managed by the managementinformation, the first object is of a different type than the secondobject, the management information is information for separatelymanaging the first object and the second object, and includes mapinformation for each first object, the map information correlates aplayback time of the corresponding first object with the location ofintra-coded picture data included in the corresponding first object, andthe management information has, as information to identify the firstobject and second object, a validity flag which indicates whether themap information for each first object and second object is valid,wherein the management information includes path information forindicating a playback sequence of the object, the path informationmanaging a time domain of the object, and the map information is a mapfor converting the time domain of the object to an address domain of theobject.